b³ Hydrae (6 Crateris) is a star in the constellation Hydra at a distance of approximately 98 light-years (about 30 parsecs) from the Sun. It has three optical companions, which are background stars located much farther away.

b³ Hydrae (WDS J10535-2008A) is a yellow-white main sequence star with the spectral type of F5V. The apparent magnitude of the star is +5.232. It has about 1.5 M_☉, its radius is about 1.9 R_☉ and the luminosity is about 6.0 L_☉. The age of the star is determined to be about 1.647 billion years.^[4] The effective temperature is about 6,505 K.

The secondary (BD−19 3124) is a yellow main sequence star of spectral type G5.^[9] The apparent magnitude of the star is +9.6.^[10] The mass is about 1.492 ± 0.001 M_☉^[11], the radius is about 2.071 ± 0.008 R_☉^[11], the luminosity is about 6.946 ± 0.001 L_☉^[11]. The effective temperature is about 6,566±1 K^[11]. It is 119.6 arcseconds away from b³ Hydrae^[12] and about 774 light-years (237 parsecs) away from the Solar System.^[11]

The third component (UCAC2 23866861) is a yellow dwarf of spectral type G.^{[citation needed]} The apparent magnitude of the star is +11.6.^[13] The mass is about 0.989 ± 0.001 M_☉^[14], the radius is about 1.315 ± 0.002 R_☉^[14], the luminosity is about 1.662 ± 0.001 L_☉^[14]. The effective temperature is about 5,761±4 K^[14]. It is separated from BD−19 3124 by 13.7 arc seconds^[12] and is about 850 light-years (260 parsecs) away from the Solar System.^[14]

The fourth component (UCAC2 23866855) is a yellow-white star of spectral type F.^{[citation needed]} The apparent magnitude of the star is +13.5.^[15] The mass is about 1.332 ± 0.001 M_☉^[16] the radius is about 1.829 ± 0.005 R_☉^[16] the luminosity is about 4.356 ± 0.001 L_☉^[16] the effective temperature is about 6,236±1 K^[16]. It is located 40.5 arc seconds away from BD−19 3124^[12] and is about 3,820 light-years (1,170 parsecs) away from the Solar System.^[16]